SAN FRANCISCO (CBS SF) — Actor-director Ben Affleck wrote a lengthy post on his Facebook page explaining his refusal to reveal an ancestor who owned slaves on the PBS show ‘Finding Your Roots.’

Affleck said he regrets asking Harvard scholar and host Henry Louis Gates, Jr. to edit out his slave-owning ancestor from the episode that aired last October.

“I didn’t want any television show about my family to include a guy who owned slaves,” Affleck wrote. “I was embarrassed. The very thought left a bad taste in my mouth.”

Affleck’s request was the subject of several emails between Sony and Gates during the filming of Batman last summer, and published on WikiLeaks last Friday. In one, a rather uncomfortable Gates asks Sony CEO Michael Lyndon whether he should grant the actor’s wishes. Lyndon tells him to comply as long as no one will know about it.

The emails provided plenty of fodder for social media, print, TV and radio pundits, with some backing the actor, but many lining up against Affleck for hiding his slave-owning ancestor. Many questioned the integrity of the PBS show for letting him censor the information.

Affleck said he lobbied Gates the same way he would “lobby directors about what takes of mine I think they should use,” and pointed out that Finding Your Roots isn’t a news program.

“I regret my initial thoughts that the issue of slavery not be included in the story,” he wrote. “We deserve neither credit nor blame for our ancestors and the degree of interest in this story suggests that we are, as a nation, still grappling with the terrible legacy of slavery. It is an examination well worth continuing. I am glad that my story, however indirectly, will contribute to that discussion. While I don’t like that the guy is an ancestor, I am happy that aspect of our country’s history is being talked about.”

The post has sparked hundreds of comments and shares.

Meantime, PBS released a statement Tuesday saying it is launching a probe into whether or not the network’s editorial standards were observed.